The Chicago Mercantile Exchange started electronic futures trading after a technical issue halted markets for as long as four hours, affecting contracts from U.S. stock indexes to Treasuries, oil and gold.

Trading, which was scheduled to start at 5 p.m. Chicago time for some products, began at 9 p.m. All day and session orders, including so-called good-til-date orders with today’s trade date, will be canceled, the bourse said.

'Clients hate it', said Evan Lucas, a Melbourne-based strategist at IG Ltd., a provider of equity-index, commodities and currencies trading, about the outage. 'They couldn’t increase or more importantly shut positions, but there is nothing you can do'.